The present invention relates to a foamed ceramic panel which is light, capable of being made in a large size, ornamental or decorative, superior in fireproofness, refractoriness, and corrosion-resistance; and to a method of producing the same.
Hitherto, a panel made of inorganic raw materials such as tile and roof tile is produced by shaping raw materials, drying the shaped body, glazing a surface of the shaped body, and burning it to vitrify the surface thereof, so that the surface water absorption of the panel is prevented and a fine spectacle thereof is presented.
In the case of a foamed ceramic panel, however, a base layer comprising foamable raw materials and a glaze layer cannot be burned at the same time, because the base layer has much larger expansion coefficient than tha glaze layer and therefore cracks are generated in the glaze layer. On the other hand, when the base layer is glazed after being burned, there are caused several problems that many manufacturing processes are required; when reinforcing bars are embedded in the base layer, the reinforcing bars are deteriorated; and cracks are generated in the base layer because thermal stress is generated therein due to a large temperature difference between a surface portion of the base layer and a core or inner portion thereof on burning the glaze layer. Further, pinholes are likely to arise because the surface of the foamed ceramic panel is porous. The surface is microscopically rough like a surface of an orange due to traces or marks of foamed particles, though the surface might be expressed to be macroscopically smooth. Thus, there cannot be obtained a smooth surface like a glass surface.
Further, the surface strength of the foamed ceramic panel is low since the panel is only coated with a thin film-like coating formed by a foaming.
Still further, when pattern is formed on or given to a surface of the foamed ceramic panel, the pattern is transferred to the surface of the panel using, for example, a printing paper made by a copper plate. This printing paper is made by coating paste-containing ink on an etched copper plate (a kind of mold), laminating a paper thereon, drying the paper, and peeling off the same. A pattern is transferred to the panel by getting the paper colored with coloring materials wet with water, putting the papter onto the panel, and peeling off the paper. Then the panel is burned to obtain a pattern. In this method using printing papers, however, the manufacturing process becomes complicated. Further, the productivity is poor and the quality of obtained pattern is not stable. Concretely speaking, on peeling off the paper, the transferred pattern is likely to go out of order, so that the quality of pattern is not stable. The pattern also goes out of order by the foaming of the base layer.
Accordingly, there is no other way to decorate a foamed ceramic panel than putting a relief pattern on the panel or coloring the whole panel. So, in the conventional method, neither desirable fine multicolor pattern nor distinct pattern (such a pattern that can be seen clearly, sharply or distinctly) has been able to be obtained.
The present invention was made to solve the above-mentioned problems, and it is an object of the present invention to provide a foamed ceramic panel and a method of producing the same wherein a fine glass-like ceramic layer is integrated with a foamed layer using a ceramic layer in order to improve the surface smoothness, decoration, surface strength and the like which have been thought to be drawbacks inherent in the foamed ceramic panel, while making the best use of distinguished features of the foamed ceramic panel, i.e. lightness, heat-insulation, refractoriness, workability, water or moisture proofness, and capability of being made in a large size.